Apparatus for coating a lapping plate platen, and related methods of using

ABSTRACT

The present disclosure involves apparatuses and methods for coating a lapping plate with an aqueous composition. The apparatus can be configured and the aqueous composition can be formulated so that the aqueous composition can flow to a spray nozzle device solely due to gravity in a batchwise manner.

RELATED APPLICATION

The present nonprovisional patent application claims the benefit ofcommonly owned provisional Application having Ser. No. 62/720,220; filedon Aug. 21, 2018, which provisional application is incorporated hereinby reference in its entirety.

BACKGROUND

The present disclosure relates to apparatuses and related methods forcoating a lapping plate that can be used to lap (abrade) one or morebars of sliders. Sliders can be made out of ceramic material such as atwo phase mixture of alumina and titanium-oxide (also referred to asAlTiC).

SUMMARY

Embodiments of the present disclosure include a method of coating alapping plate platen, wherein the method comprises:

a) providing a first volume of an aqueous composition in a container,wherein the aqueous composition comprises:

-   -   i) a solid resin powder;    -   ii) a plurality of solid abrasive particles; and    -   iii) an aqueous carrier;

b) providing a spray nozzle device in fluid communication with thecontainer;

c) spraying a second volume of the aqueous composition onto anunderlying lapping plate platen to form a layer of an aqueouscomposition on the surface of the platen, wherein the aqueouscomposition has a viscosity so that the aqueous composition can flowfrom the container to the spray nozzle device due to gravity.

Embodiments of the present disclosure also include an apparatus forcoating a lapping plate platen, wherein the apparatus comprises:

a) a container having a capacity to contain a first volume of an aqueouscomposition, wherein the aqueous composition comprises:

-   -   i) a solid resin powder;    -   ii) a plurality of solid abrasive particles; and    -   iii) an aqueous carrier;

b) a spray nozzle device coupled to the container so that a secondvolume of the aqueous composition having a viscosity can flow from thecontainer to the spray nozzle device due to gravity;

c) a mounting device configured to mount the lapping plate platen,wherein the spray nozzle device is configured to spray the second volumeof the aqueous composition onto the underlying lapping plate platen toform a layer of an aqueous composition on the surface of the platen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view showing an apparatus for coatinga lapping plate platen;

FIG. 1B is a schematic perspective view showing a close-up of thecontainer in the apparatus of FIG. 1A when the container is initiallyfilled with a coating composition;

FIG. 1C is a schematic perspective view showing a close-up of thecontainer in the apparatus of FIG. 1A after a lapping plate platen hasbeen coated with the coating composition according to a batch process;and

FIG. 1D is a schematic close up view of the spray nozzle device andcontainer shown in FIG. 1A.

DETAILED DESCRIPTION

A lapping plate according to the present disclosure can be used in alapping tool/apparatus to abrade the surface of a slider (e.g., art airbearing surface). If desired, a slurry can be applied to the lappingsurface of a lapping plate to enhance the abrasive action as the lappingsurface is rotated relative to a slider bar containing a plurality ofthe sliders held in a pressing engagement against the lapping surface. Alapping plate according to the present disclosure can be used for avariety of lapping processes such as rough lapping, fine lapping, andkiss lapping.

A lapping plate platen according to the present disclosure can be madeof one or more layers and/or of one or more materials in each layer. Asdiscussed below, abrasive particles, solid resin powder, and an aqueouscarrier can be applied to a surface of a platen. In some embodiments, aplaten according to the present disclosure can be made out of one ormore materials such as plastic, metals, and the like. In someembodiments, at least the surface that the abrasive particles, solidresin powder, and aqueous carrier are applied to is made out of one ormore metals. Exemplary metals include at least one of tin, tin alloy,aluminum, copper, combinations of these, and the like.

Embodiments of the present disclosure include a spray system configuredto apply a coating composition to a lapping plate platen to form alapping plate. A non-limiting example of a spray system and methodaccording to the present disclosure is described herein below withrespect to FIGS. 1A-1D.

FIG. 1A shows a schematic, perspective view of an apparatus 100 forcoating a lapping plate platen 101. As shown in FIG. 1, apparatus 100includes a container 102 in fluid communication with a spray nozzledevice 104. The container 102 is physically coupled to and is in fluidcommunication with spray nozzle device 104 via piping 103. As shown inFIG. 1A, lapping plate platen 101 is mounted to rotatable mountingdevice 105 that can rotate (as indicated by arrow 106) while a coatingcomposition is sprayed 106 onto lapping plate platen 101.

A container 102 can have a variety of capacities. In some embodiments,as discussed further below, the capacity of a container can permit theapparatus to coat a lapping plate platen in a batch manner while havinga relatively small amount of residual coating composition remaining inthe container after coating. Further, the configuration (e.g., diameterand height) of a container 102 can be selected so that for a given batchvolume of aqueous composition provides a “head” pressure that can forcethe aqueous composition to flow through piping 103 at a desirable flowrate into spray nozzle device 104. In some embodiments, a container 102can include graduation markings (e.g., a graduated cylinder) that showthe volume at various locations to assist in filling with coatingcomposition. In some embodiments, the container can have a capacity from10 to 500 milliliters, or even from 30 to 200 milliliters.

As shown in FIG. 1A, piping 103 can be relatively short and providefluid communication between container 102 and spray nozzle device 104.In some embodiments, as shown in FIG. 1A, the container 102 is locatedabove and relatively close to the opening into spray nozzle device 104so that, as discussed below, the aqueous composition can flow throughappropriately sized piping 103 at a desired flowrate directly into thespray nozzle device 104 due solely to gravity. The diameter and lengthof piping can influence the flow rate of the aqueous composition.Increasing the diameter and/or decreasing the length of piping 103 canincrease flow rate. Decreasing the diameter and/or increasing the lengthof piping 103 can decrease flow rate. In some embodiments, the piping103 can have a outside diameter in the range from 1 to 10 millimeters,or even from 2 to 5 millimeters. In some embodiments, the length ofpiping 103 can be in the range from 10 to 70 millimeters, or even from30 to 60 millimeters. Piping 103 can advantageously avoid relativelylong fluid delivery lines, which can waste coating material that is notsprayed onto a lapping plate platen and/or can avoid particlesedimentation that may occur when the coating composition is not flowingthrough the line, e.g., when lapping plate platens are being transferredout of and/or into the apparatus 100.

A spray nozzle device according to the present disclosure is configuredto spray an aqueous composition onto the underlying lapping plate platento form a layer of an aqueous composition on the surface of the platen.The aqueous composition can be cured and become an abrasive layer on thesurface of the lapping plate platen.

An example of a spray nozzle device is illustrated in FIGS. 1A and 1D.As shown in FIG. 1D, a coating composition is provided in container 102and can flow via gravity through piping 103 and into spray nozzle device104 as shown by path 111. A flow of pressured gas 110 can be supplied tospray nozzle 104 so that it can mix with the coating composition atpoint 112 and atomize the coating composition into spray 106.

An example of a spray nozzle device that is commercially availableincludes a high volume, low-pressure (HVLP) automatic airspray gun soldunder the tradename A35 automatic airspray gun from Kremlin-Rexson(Stains Cedex-France).

The flow rate of an atomized aqueous composition from nozzle device 104can be influenced by (in addition to other factors as described hereinsuch as liquid viscosity) the size of the spray nozzle or nozzles, theatomization gas pressure, and/or any other componentry in the flow pathof nozzle device 104.

In some embodiments, as shown in FIG. 1A, apparatus 100 can also includea controller 120 in electrical communication 121 with one or morecomponents (e.g., spray nozzle device 104 and rotatable mounting device105) of apparatus 100 to execute one or more functions as describedherein with respect to exemplary methods. For example, controller 120can open a valve of the spray nozzle device 104 to spray aqueous coatingcomposition 106 onto an underlying lapping plate platen 101. Controller120 can also close the valve to stop spraying. In some embodiments,apparatus 100 can simply include a solenoid valve to turn a gas supplyfor atomization in nozzle device 104 on or off.

Now, an example of coating a lapping plate platen is described withrespect to FIGS. 1A-1C.

In some embodiments, a method according to the present disclosureincludes providing a first volume 150 of an aqueous composition incontainer 102. The aqueous composition can include a solid resin powder,a plurality of solid abrasive particles, an aqueous carrier, andoptionally, one or more additives. An example of an aqueous, coatingcomposition is described in U.S. Pub. No. 2017/0304988 (Moudry et al.),wherein the entirety of said publication is incorporated herein byreference.

Solid resin powder according to the present disclosure can include asolid resin powder that can be applied to at least a portion of thesurface of a platen and subsequently cured so that the solid, uncuredresin powder melts and flows to form, along with abrasive particles, acontinuous cured coating suitable for lapping a bar of sliders. Becausethe resin powder is solid, it can be applied to the surface of a platenin solid form.

A solid resin powder can be selected based on one or more of itscharacteristics such as the ability to be sprayed via apparatus 100, howthe resin performs in forming a coating on a platen, how the resinperforms in an abrasive coating during lapping, combinations of these,and the like. For example, a resin powder can be selected to helpprovide the abrasive coating with desirable chemical and mechanicalresistance during lapping. As another example, a solid resin powder canbe selected based on one or more of average particle diameter, particledensity, and overall amount by weight to be used so that the solid resinpowder interacts with the abrasive particles and aqueous carrier in adesired manner during application and in the final coating (furtherdiscussed below).

Solid resin powder can have an average particle diameter that permitsthe solid resin powder to be applied to a platen in a desirable manner.For example, the average particle diameter can be a size that permitsthe solid resin powder to be handled and dispensed (e.g., sprayed) byequipment discussed below. In some embodiments, solid resin powder canhave an average particle diameter in the range from 0.1 to 100micrometers, from 0.1 to 20 micrometers, or even from 0.1 to 5micrometers.

Solid resin powder can have a particle density that permits the solidresin powder to be applied to a platen in a desirable manner. In someembodiments, solid resin powder can have a particle density in the rangefrom 0.5 to 50 grams per cubic centimeter, from 0.5 to 20 grams percubic centimeter, or even from 1 to 10 grams per cubic centimeter.

A solid resin powder can be made out of one or more materials from amonga wide variety of chemistries. In some embodiments, a solid resin powderincludes thermosetting solid resin powder. In some embodiments, a solidresin powder is selected from the group consisting of solid epoxy resinpowder, solid vinyl resin powder, solid polyester resin powder, andblends thereof. In some embodiments, the solid resin powder is polyesterresin. Exemplary solid resin powder is commercially available under thetradename 1 Coat Silver polyester resin powder from MC Industries, WhiteCity, Oreg., or the tradename Epoxy Primer epoxy resin powder from NICIndustries, White City, Oreg.

A plurality of abrasive particles according to the present disclosurecan include abrasive particles than can be applied to at least a portionof the surface of a platen and form, along with cured resin, an abrasivecoating suitable for lapping a bar of sliders.

Abrasive particles can be selected based on one or more of theircharacteristics such as the ability to be sprayed via apparatus 100, howthe abrasive particles influence the forming of the abrasive coating ona platen, how the abrasive particles perform in an abrasive coatingduring lapping, combinations of these, and the like. For example,abrasive particles can be selected to help provide the abrasive coatingwith desirable abrading characteristics during lapping. As anotherexample, abrasive particles can be selected based on one or more ofaverage particle diameter, particle density, and overall amount byweight to be used so that the abrasive particles interact with the solidresin powder and/or aqueous carrier in a desired manner. For example,one or more of average particle diameter, particle density, and overallamount of each of the solid resin powder and abrasive particles can beselected to help prevent either the abrasive or resin from settling outof a mixture of the two in an aqueous carrier (e.g., during mixing,storing (e.g., in a container), during application to a platen, or whileon the surface of a platen).

Abrasive particles can have an average particle diameter that permitsthe abrasive particles to be applied to a platen in a desirable manner.The average particle diameter of the abrasive particles can be selecteddepending on whether lapping involves rough lapping, fine lapping,and/or kiss lapping. In some embodiments, the abrasive particles canhave an average particle diameter in the range from 0.01 to 10micrometers. In some embodiments, the abrasive particles can have anaverage particle diameter less than 0.1 micrometers (e.g., for “kiss”lapping). In some embodiments, the abrasive particles can have anaverage particle diameter in the range from 0.1 to 1 micrometers (e.g.,for “fine” lapping). In still other embodiments, the abrasive particlescan have an average particle diameter in the range from greater than 1micrometer to 3 micrometers (e.g., for “rough” lapping).

Abrasive particles can have a particle density that permits the abrasiveparticles to be applied to a platen in a desirable manner. In someembodiments, the abrasive particles can have a particle density in therange from 0.5 to 50 grams per cubic centimeter, from 0.5 to 20 gramsper cubic centimeter, or even from 1 to 10 grams per cubic centimeter.

Abrasive particles according to the present disclosure can be made outof one or more materials. In some embodiments, abrasive particles areselected from the group consisting of diamond particles, cubic boronnitride particles, alumina particles, alumina zirconia particles,silicon carbide particles, and combinations thereof. In someembodiments, abrasive particles can be embedded within a ceramicmaterial such as embedded diamond particles (embedded abrasive particlescan also be referred to as encapsulated or composite abrasive particles,or even abrasive beads). Embedded abrasive particles are larger in sizeas compared to bare abrasive particles because the abrasive particlesare embedded within ceramic material. For example, in some embodiments,embedded abrasive particles can have an average particle diameter in therange from 10 to 50 micrometers.

An aqueous carrier can provide a medium for the solid resin powder andabrasive particles to be suspended so that the solid resin powder andabrasive particles can be sprayed on a surface of a platen so as to forma layer so that the solid resin powder can eventually be cured to helpform an abrasive coating.

An aqueous carrier can include at least water. In some embodiments, anaqueous carrier can include water and a dispersant. A dispersant canhelp facilitate dispersing the solid resin powder and/or abrasiveparticles in water so as to form a suspension of the solid resin powderand/or abrasive particles in liquid water. In some embodiments, adispersant includes at least one surfactant. Exemplary surfactantsinclude anionic surfactants, nonionic surfactants, and mixtures thereof.

A dispersant can be present in the aqueous carrier in a variety ofamounts. In some embodiments, the dispersant can be present in theaqueous carrier in an amount of 10 percent or less by weight based onthe total weight of the aqueous carrier, or even 5 percent or less byweight based on the total weight of the aqueous carrier.

In some embodiments, an aqueous carrier can include one or more organicsolvents. An exemplary organic solvent includes 1-Methyl-2pyrrolidone(NMP). In some embodiments, the organic solvents can be included in anamount of 10 percent or less by weight based on the total weight of theaqueous carrier. In some embodiments, the organic solvents can beincluded in an amount of 5 percent or less by weight based on the totalweight of the aqueous carrier. In some embodiments, the organic solventscan be included in an amount of 1 percent or less by weight based on thetotal weight of the aqueous carrier.

An example of an aqueous carrier suitable for forming a suspension ofsolid resin powder and abrasive particles is commercially availableunder the tradename “Liquid 2 Powder” from Powder Buy The Pound,Nolensville, Tenn.

If the abrasive particles and solid resin powder are applied to a platensequentially, the aqueous carrier used with each of the abrasiveparticles and solid resin powder can be the same or different as long aseach aqueous carrier is compatible with the other.

Each of the solid resin powder, plurality of abrasive particles, andaqueous carrier can be included in an aqueous composition in an amountso as to facilitate coating, while at the same time providing desirablecoating properties for lapping. In some embodiments, aqueous carrier andthe total of the solid resin powder and the plurality of abrasiveparticles are present in the aqueous composition in an amount so thatthe weight ratio of the total of the solid resin powder and plurality ofabrasive particles to the aqueous carrier is in the range from 1 to 10,from 1 to 5, from 1 to 3, or even 1 to 1.2.

In some embodiments, each of the solid resin powder and the plurality ofabrasive particles are present in an amount so that the weight ratio ofthe solid resin powder to the plurality of abrasive particles in theabrasive coating is in the range from 0.1 to 10, from 0.25 to 5, or evenfrom 0.5 to 1.5.

In some embodiments, the average particle diameter of each of the solidresin powder and the abrasive particles can be selected so that theratio of the of the solid resin powder average particle diameter to theabrasive particles average particle diameter is in the range from 0.5:1to 5:1, from 0.5:1 to 2:1, or even from 0.5:1 to 1.5:1.

In some embodiments, the particle density of each of the solid resinpowder and the abrasive particles can be selected so that the ratio ofthe of the solid resin powder particle density to the abrasive particlesparticle density is in the range from 0.1 to 10, from 0.25 to 5, from0.5 to 1.5, or even from 0.8 to 1.2.

One or more optional additives can be included in an aqueous compositionaccording to the present disclosure. Exemplary optional additivesinclude fillers, pigments, and the like. An aqueous composition can beformed by a variety of techniques. For example, solid resin powderand/or a plurality of abrasive particles can be combined with an aqueouscarrier and mixed so that the solid resin powder and/or abrasiveparticles become suspended in the aqueous carrier to form an aqueouscomposition that can be applied to a surface of a platen. The solidresin powder and a plurality of abrasive particles can be applied to thesurface of the platen sequentially or as a mixture in a single step. Insome embodiments, an aqueous composition that includes an aqueouscarrier and both the solid resin powder and the plurality of solidabrasive particles (and one or more optional additives) can be appliedto the surface of the platen in a single step.

The aqueous composition can be applied to the platen immediately afterforming the aqueous composition or stored for a period of time in acontainer. Being able to apply the solid resin powder and abrasiveparticles in a single step can advantageously avoid, if desired,manufacturing protocols that apply a resin and abrasive particles in twoor more steps. For example, an abrasive coating made from a two partliquid epoxy system (resin plus hardener) can be formed by applying thefirst part epoxy, the second part hardener, and then the abrasiveparticles. Such a three step process can lead to increased process time,a non-uniform coating on a platen, and/or inconsistent coatings amongmultiple platens.

In some embodiments, the aqueous composition can be applied to a lappingplate according to a batch process. For example, referring to FIG. 1Bagain, the first volume 150 is an amount that can fully coat no morethan one lapping plate platen of the same size as the lapping plateplaten yet permit some residual amount of aqueous composition to remainin container 102 after coating a lapping plate.

In some embodiments, before providing the first volume 150 of theaqueous composition in container 102, the aqueous composition can beformed by combining and mixing the components for a desired period oftime (e.g., mixing at 1000-4000 rpms with a mixer for 3-10 minutes). Ifdesired, the aqueous composition can be stored for a period time. As thedesired time, the aqueous composition can be agitated to suspend thesolid resin powder and plurality of solid abrasive particles throughoutthe aqueous carrier (e.g., manually shaken for 15-60 seconds). Byhandling the aqueous composition in this way, continuous mixing is notnecessary, which can advantageously avoid undue damage to abrasiveparticles. After agitating, the first volume 150 of the aqueouscomposition can be provided in container 102. The first volume 150 canbe in the range from 10 to 500 milliliters, or even from 30 to 200milliliters.

A lapping plate platen 101 to be coated can mounted on mounting device105 and rotated while a second volume of the aqueous composition issprayed onto the underlying lapping plate platen 101 to form a layer ofan aqueous composition on the surface of the platen 101. The aqueouscomposition can be permitted to flow by, e.g., supply atomization gas tonozzle device 104. After a desired amount of aqueous composition hasbeen sprayed, the spraying can be stopped. As shown in FIG. 1C, a thirdvolume 155 of the aqueous composition remains in the container 102,where the third volume 155 is less than the second volume applied to thelapping plate platen. By leaving a residual amount (third volume 155) ofaqueous composition in container 102, introducing gas (e.g., air)through piping 103 can be avoided. Introducing gas through piping 103can lead to undue “sputtering” of aqueous composition from nozzle device104, which can lead to non-uniform coating of the aqueous composition onlapping plate platen 101.

In some embodiments, the aqueous composition has a viscosity so that theaqueous composition can flow from the container 102 to the spray nozzledevice 104 due to solely to gravity. Accordingly, the aqueouscomposition can be formulated to accommodate this. For example, theaqueous composition can be formulated so that the aqueous compositionhas a Brookfield viscosity of 150 centipoise or less when measured at21° C. and 60 rpm with a #3 spindle. In some embodiments, the aqueouscomposition has a Brookfield viscosity of 125 centipoise or less, 110 orless, or even 100 or less when measured at 21° C. and 60 rpm with a #3spindle.

As shown in FIG. 1A, the container 102 is open to atmospheric pressureand is not a pressurized container so that the aqueous composition canflow solely due to gravity.

Advantageously, by formulating the aqueous composition so that it can beapplied in a batch manner and flow to spay nozzle device 104 due solelyto gravity, the coating apparatus and methodology according to thepresent disclosure can provide desirable volume control and/or avoidrelatively long supply lines to the spray nozzle device, which can avoidundue settling of abrasive and/or resin particles in the lines.

After applying a coating of the aqueous composition onto the lappingplate platen 101, the aqueous carrier can be evaporated and the solidresin powder can be cured to form an abrasive coating comprising thesolid abrasive particles and the cured resin.

What is claimed is: 1) A method of coating a lapping plate platen,wherein the method comprises: a) providing a first volume of an aqueouscomposition in a container, wherein the aqueous composition comprises:i) a solid resin powder; ii) a plurality of solid abrasive particles;and iii) an aqueous carrier; b) providing a spray nozzle device in fluidcommunication with the container; c) spraying a second volume of theaqueous composition onto an underlying lapping plate platen to form alayer of an aqueous composition on the surface of the platen, whereinthe aqueous composition has a viscosity so that the aqueous compositioncan flow from the container to the spray nozzle device due to gravity.2) The method of claim 1, further comprising stopping the spraying theaqueous composition, wherein a third volume of the aqueous compositionremains in the container, and wherein the third volume is less than thesecond volume. 3) The method of claim 1, wherein the first volume is anamount that can fully coat no more than one lapping plate platen of thesame size as the lapping plate platen. 4) The method of claim 1, whereinthe aqueous composition has a Brookfield viscosity of 150 centipoise orless when measured at 21° C. and 60 rpm with a #3 spindle. 5) The methodof claim 1, wherein providing the first volume comprises: a) agitatingthe first volume to suspend the solid resin powder and plurality ofsolid abrasive particles throughout the aqueous carrier, whereinagitating is performed for a time period of 10 minutes or less; and b)transferring the first volume to the container after step (a). 6) Themethod of claim 1, further comprising, after step (c): a) evaporatingthe aqueous carrier; and b) substantially curing the solid resin powderto form an abrasive coating comprising the solid abrasive particles andthe cured resin. 7) The method of claim 1, wherein the aqueous carriercomprises water and a dispersant. 8) The method of claim 7, wherein thedispersant comprises a surfactant, and wherein the dispersant is presentin an amount of 10 percent or less by weight based on the total weightof the aqueous carrier. 10) An apparatus for coating a lapping plateplaten, wherein the apparatus comprises: a) a container having acapacity to contain a first volume of an aqueous composition, whereinthe aqueous composition comprises: i) a solid resin powder; ii) aplurality of solid abrasive particles; and iii) an aqueous carrier; b) aspray nozzle device coupled to the container so that a second volume ofthe aqueous composition having a viscosity can flow from the containerto the spray nozzle device due to gravity; c) a mounting deviceconfigured to mount the lapping plate platen, wherein the spray nozzledevice is configured to spray the second volume of the aqueouscomposition onto the underlying lapping plate platen to form a layer ofan aqueous composition on the surface of the platen. 11) The apparatusof claim 10, further comprising a controller comprising programinstructions comprising: a) opening a valve of the spray nozzle deviceto spray the second volume of the aqueous composition onto an underlyinglapping plate platen; and b) closing the valve to stop spraying. 12) Theapparatus of claim 10, wherein the container has a capacity to operate abatch process.